1. Field of the Invention
The present invention relates to a method of preventing the atmosphere from entering a container in an inoperative state which is adapted to temporarily reserve therein a low-temperature liquefied gas, which is then supplied therefrom to an object through an outlet device such as a nozzle.
2. Description of the Prior Art
In use of a low-temperature liquefied gas such as liquid nitrogen, the gas is often supplied from a storage-supply source (e.g., a cold evaporator) to a heat-insulating container so as to be temporarily stored and then dripped or allowed to flow down through an outlet device such as a nozzle provided at the container. In such a usage, when the low-temperature liquefied gas is not used over a considerably long period of time, for example, a period from the end of one day's operation to the start of operation on the following day, i.e., when no low-temperature liquefied gas is supplied to the container from the storage-supply source, the container becomes empty. In consequence, the atmosphere enters the container through openings such as an outlet port of the outlet device and a gas discharge port of the container, and the moisture and carbon dioxide included in the atmosphere may cling, in the form of pieces of ice and frost, to the container inner wall and the outlet device surface which are cold. In the case where these ice pieces and the like are formed on the outlet device surface, as a matter of course, they will undesirably cause the outlet port to be blocked up, disturbing the flow of the low-temperature liquefied gas when it is used, or decreasing the flow rate. Also, in the case where these ice pieces and the like are formed on the container inner wall, when the low-temperature liquefied gas is supplied to the container, these ice pieces and the like are often suspended in the liquid to sink, causing the outlet port to be blocked up.